There are a number of problems inherent in housing electronic circuits. One major problem is providing adequate thermal management for the electronic circuits. Electronic circuits generate heat during use and must be properly cooled in order to continue to function properly. Various conventional systems addressing the need for cooling exist, including inducing an air flow (forced convection), natural convection and radiation. Other alternatives include circulating liquid, to carry thermal energy from heat exchangers coupled to the heat source to external radiators or coolers.
Conventional systems that operate by inducing an air flow typically utilize fans or blowers to move air directly over the circuitry requiring cooling. In a system having multiple electronics enclosures, such as a rack-shelf system, there may be multiple fans/blowers, e.g., one or more per enclosure, which induce air flow across their own associated circuit boards. Alternatively, there might be one large fan for the entire rack-shelf system, inducing air flow across all circuit boards simultaneously.
Such conventional cooling systems need to address a number of challenges. One problem addressed by the disclosure herein is that the most appropriate cooling approach for a certain electronic chassis may be dependent upon the installation details of the unit. Some equipment rooms may be optimized for front-to-rear (“FTR”) ventilation while others may be optimized for rear-to-front (“RTF”) ventilation. In some conventional solutions, two fan modules are available, one optimized for FTR and the other for RTF, and the appropriate one is selected at the time of installation.
In some applications, merely reversing the electrical feed to the fan may reverse operation of the fan and therefore the ventilation direction. However, for fans powered by alternating current this option is not available, and even for direct current fans many aspects of fan design, including blade geometry, filter and louver designs, and the like, are optimized for a particular direction of flow. Therefore, merely reversing the rotational direction of a fan itself is often not an optimal solution.
What is needed is a simple and inexpensive manner to address the fact that the most appropriate manner of ventilation of an electronics enclosure may depend on the environment in which it is installed.